1. Field of the Invention
The invention relates to a Ni—MH (nickel-metal hydride) or NiCd (nickel-cadmium) secondary battery charger, and more particularly, to a charger with charging grooves at both sides thereof. Moreover, the charger is suitable for charging different types of batteries.
2. Description of the Related Art
With the popularity of portable electronic products like digital cameras, MP3, PDA, etc., the demand for secondary batteries is considerably raised. The problem of the electronic products using the secondary batteries lies in the inconvenience of access to the power source when the user going out for a business trip uses up the energy in the battery.
As shown in FIGS. 1A and 1B, a charger 10 includes a plug 11 at the bottom thereof. The plug 11 is adapted to insert into an AC mains. A charging electronic unit 12 is disposed within the charger 10. The charging electronic unit 12 includes a positive and a negative charging terminal 121, 122 projecting from the front and the rear wall of a charging groove 13 for charging the secondary batteries 20.
However, the conventional charger 10 is connected to an AC mains socket (not shown) with the aid of the plug 11. As a result, the charger 10 requires an AC-DC-converter 14 for providing the charging electronic unit 12 with the required DC voltage. In this way, the AC-DC-converter 14 will occupy most of the space at the front half part of the charger 10. Besides, the charging electronic unit 12 is fitted to the bottom of the charging groove 13 so that it is difficult to reduce the volume of the whole structure of the charger 10, thereby causing inconvenience in carrying it outdoors. Moreover, the plug 11 requires a corresponding AC mains socket to provide the charging power. It is also a problem that the AC mains socket is usually unavailable outdoors.
As shown in FIG. 2, a conventional USB charger 30 includes a main body 31. A connection cord 32 and a USB plug 33 are extended from the main body 31. The USB plug 33 can be plugged into an electronic product 34 (such as notebook computer) with USB socket 35 when the user is outdoors. In this way, the secondary batteries 20 in the main body 31 can be charged without problem. In comparison to the AC charger 10 according to FIGS. 1A and 1B, the USB charger 30 has the advantage of directly obtaining DC power. However, the internal arrangement of the USB charger 30 is much the same to that of the AC charger 10 only with the difference that the connection cord 32 and the USB plug 33 are employed in the USB charger 30. As a result, this kind of the USB charger 30 has also the problem of large volume. In addition, the use of the connection cord 32 is unfavorable for carrying. Thus, the use of the USB charger 30 is much restricted, too. Furthermore, the main body 31 can accommodate only one type of batteries (such as 3/AA or 4/AAA). In charging the secondary batteries of different types in one charger, the charging structure has to be changed. This will cause much inconvenience and occupy much space.
With the constant improvement of the portable electronic products, commodities like MP3 or PDA were made smaller and thinner. Moreover, many of them employ the secondary batteries (like 3/AA or 4/AAA) for providing the required power. Thus, the development of the charger for secondary batteries is toward the miniaturization and compactness. In addition, the charger that can charge different types of secondary batteries (like 3/AA or 4/AAA) can meet the requirements of the market. This is the main goal that the invention tries to achieve.